User interface for a portion of a display screen



FIG. 1 is a front view of a user interface for a portion of a display screen showing my new design; and,

FIG. 2 is an enlarged view thereof, only a portion is shown for clarity of illustration.

The broken line showing of the elements within the portion of a display screen and the unshaded areas within them form no part of the claimed design. The broken line showing of the display screen is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a user interface for a portion of a display screen, as shown and described. 